[1.9.x] Added docs about configuring CSRF support in AngularJS.

Backport of 6a4f13de27e2c46b6e516a01ba77fd4fe03d9dbe from master

docs/ref/csrf.txt

@@ -139,6 +139,14 @@ newer:
         }
     });
 
+If you're using AngularJS 1.1.3 and newer, it's sufficient to configure the
+``$http`` provider with the cookie and header names:
+
+.. code-block:: javascript
+
+    $http.defaults.xsrfCookieName = 'csrftoken';
+    $http.defaults.xsrfHeaderName = 'X-CSRFToken';
+
 Other template engines
 ----------------------